6.1 The Ego Theory and the Bundle Theory Quickly Summarized

1. In the last chapter, I gave some reasons for supposing that split-brain subjects are single persons, but I offered no theory of the nature of persons and personal identity. In this chapter, I propose such a theory.

2. The two best-known theories about the nature of per­sons are the ego theory and the bundle theory. The philoso­pher with whom the ego theory is most notably associated is Rene Descartes (1641); the most famous advocate of the bundle theory (at least in Western philosophy) is David Hume (1739). According to the ego theory, in its Cartesian form, persons are continuing, spiritual substances, whose essence is consciousness. What unifies different experiences I have at the same time, indeed what unifies my entire men­tal history, is the fact that all the relevant experiences are had by the continuing spiritual substance that is me. The ego theory thus grounds subject unity for experiences on same­ness of spiritual substance.

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   The bundle theory draws on the observation that the experiences, thoughts, and other mental states of a single

4. person stand in various causal relations to one another—for example, experiences cause introspective awareness of themselves as well as later memories—and thereby they are linked or bundled together. Each person, according to the bundle theory, is no more than a mental bundle. Not every mental bundle is a person, however. A person, for the bun­dle theorist, is an appropriately complex bundle, standardly one that includes "higher-order" beliefs, desires, and inten­tions connected to other mental states in the relevant ways. We may say that persons are the subjects of experiences; but this talk is misleading, according to the bundle theorist, at least if it is taken to imply that persons are substances. Persons are nothing over and above temporally extended clusters of mental events. And subject unity is no more than sameness of mental bundle.

6.2 Objections to the Ego Theory

(4) It has been suggested (by Parfit 1984) that the ego the­ory, in its classical form, is incompatible with split-brain cases. According to Parfit, each split-brain subject is a single person, albeit one whose consciousness is divided. The ego theory, he claims, cannot allow such a division, for, as just noted, if the ego theory is true then what unifies a person's experiences is simply the fact that they are undergone by the same spiritual substance.

This is not fully convincing, however. The ego theory pro­vides an account of subject unity for persons, not phenomenal unity. Split-brain patients, I have maintained, undergo expe­riences that are phenomenally disunified but not subject disunified. If, as I argued earlier, there is no difficulty in supposing that one and the same person undergoes distinct simultaneous experiences in the same sense-modality, then, if persons are spiritual substances, the same is true of spiri­tual substances.

Of course, on the ego theory, persons are spiritual sub­stances whose essence is consciousness, and Parfit would no doubt insist that creatures with an essence of this sort can­not have a divided consciousness without splitting into two themselves. However, there is no obvious contradiction in the idea that a single spiritual substance, whose essence is to undergo experiences, feelings, and conscious thoughts, has a phenomenally disunified consciousness in certain special situations while retaining a unified consciousness else­where. So, the claim that the ego theory in its classical form is shown to be mistaken by split-brain cases is unjustified, at least if one agrees with the view defended in chapter 5 of those cases.

5. The classical ego theory has other troubles. For if minds are spirits, it is very difficult to believe that the mental is ever causally efficacious with respect to the physical, given the abundant evidence for the causal closure of the physical world. Moreover, none of the historical arguments supports such metaphysical profligacy. So, Occam's razor counts against the postulation of spiritual substances.

6. To this, the present-day ego theorist may retort that the classical view needs to be redressed in materialist clothing. Persons should be identified not with spiritual substances but rather with material substances, whose mental histories are unified by being histories of states of those substances. There are strong objections to any such revised proposal, however.

7. Consider first body transplants. While physicians can­not now transplant my brain into your body or vice versa, it is certainly conceivable that one day they will be able to per­form such an operation. And if they do, then surely the right thing to say is that, once the operation is over, I will have your body. For the person speaking with your voice will have my memories, my character traits, and my psychologi­cal dispositions.

One familiar way of making this point more vivid is to suppose that after a double switch in which my brain is put into your body and yours is put into mine, you get to choose which of the two people afterward will be tortured and which rewarded. Leaving to one side moral considerations that may influence your decision, unless you are a masochist or you like me more than you like yourself, you will surely choose that the person now with your body is to be tortured. For that person is no longer you. But if there can be the same

live human body at two different times without the same person, then personal identity is not secured by identity of body.

(8) Another reason not to adopt the view that persons are material substances is provided by the phenomenon of mul­tiple personality disorder, discussed briefly in chapter 5. This phenomenon undermines not only the view that per­sons are the same as bodies but also the alternative material­ist view that persons are the same as brains. For where there is a multiple personality disorder, there is one brain and one body but multiple persons. Consider, for example, the fol­lowing case of Rene, a young woman who, as a child, was beaten, burned, and sexually abused by her parents, as described in Confer and Ables (1983):

Rene was a bewildered and frightened woman. She was continu­ally preoccupied with multiple experiences of which she could make no sense and over which she had no control. For example, she would find a number of skimpy, sexy bathing suits in her closet which her husband stated she insisted he buy for her, along with clothes that were too tight and too short. She had no memory of purchasing any of these. Similarly, bills would come in at the end of the month for car rentals and air travels she knew nothing of. Even worse, she would awaken on occasion to find herself in a strange motel and town with no knowledge of where she was or how she got there. . . . (p. 51)

Rene, we are told, had several alternate personalities. One of these was Stella.

This . .. alternative was sultry and seductive. She apparently knew how to please others and spent her time doing this. For example, she pleased men by "taking them to paradise." Frequently, she took . . . trips to other cities where she engaged in sexual liaisons with men. Rene would then emerge, awakening in a strange room with a strange man and feel horrified. (p. 53)

Stella was impulsive and inattentive to the consequences of her actions. . . . She would charge hundreds of dollars of clothing or go on a trip to Mexico at a moment's notice. . . .

She reported watching behind the porch on Easter of Rene's eleventh year when her father coaxed Rene into the house and bloodily raped her. . . . She described herself as Rene's best friend. (p. 54)

9. Another multiple personality case, in some ways even more clearcut, is that of Mary Reynolds (1793-1854), as described by Sutcliffe and Jones (1962) (and noted in Marks 1980):

Her disorder was first noticed at 18 (1811). Before her alterations, she was described as a well-educated woman, of dull and melan­choly temperament, living in the wilds of Pennsylvania. Her per­sonality changed following a long and profound sleep. She awoke disoriented, no longer able to recognize relatives. . . . Previously reserved, taciturn and timid, she was now friendly, merry, and adventurous with a new interest in the outdoors. There was no regaining of self-reference memories or reestablishing of old per­sonal relationships in "the second state." . . . After five weeks in State 2, on this first occasion, Miss R. returned to her old state (State 1), following a further profound sleep. Now, in State 1, there was no memory for the intervening State 2 period. Alternations between these two mutually amnesic phases went on for 15/16 years. Memory was continuous within each of the phases.

Intuitively, in both of the above cases, there are two different persons, each with her own, separate mental history. Once again, the ego theory, in its materialist form, is in trouble.